Optparse, the old version just ignores all unrecognised arguments and carries on. In most situations, this isn't ideal and was changed in argparse. But there are a few situations where you want to ignore any unrecognised arguments and parse the ones you've specified.
For example:
parser = argparse.ArgumentParser()
parser.add_argument('--foo', dest="foo")
parser.parse_args()
$python myscript.py --foo 1 --bar 2
error: unrecognized arguments: --bar
Is there anyway to override this?
Replace
args = parser.parse_args()
with
args, unknown = parser.parse_known_args()
For example,
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--foo')
args, unknown = parser.parse_known_args(['--foo', 'BAR', 'spam'])
print(args)
# Namespace(foo='BAR')
print(unknown)
# ['spam']
parse_known_args
parser.parse_args(None) rather than parser.parse_args([]) in my tests.
parse_known_args rather than parse_args enables the use of ArgumentParser in code within the scope of if __name__ == 'main': (a condition that is True for all cells in an IPython Notebook ... which I find greatly aids the development and testing code that I want to eventually migrate to a script invoked from a command line)
You can puts the remaining parts into a new argument with parser.add_argument('args', nargs=argparse.REMAINDER) if you want to use them.
parse_args() and doesn't require parse_known_args() (on Python 2.7).
Actually argparse does still "ignore" _unrecognized_args. As long as these "unrecognized" arguments don't use the default prefix you will hear no complaints from the parser.
Using @anutbu's configuration but with the standard parse.parse_args(), if we were to execute our program with the following arguments.
$ program --foo BAR a b +cd e
We will have this Namespaced data collection to work with.
Namespace(_unrecognized_args=['a', 'b', '+cd', 'e'], foo='BAR')
If we wanted the default prefix - ignored we could change the ArgumentParser and decide we are going to use a + for our "recognized" arguments instead.
parser = argparse.ArgumentParser(prefix_chars='+')
parser.add_argument('+cd')
The same command will produce
Namespace(_unrecognized_args=['--foo', 'BAR', 'a', 'b'], cd='e')
Put that in your pipe and smoke it =)
nJoy!
